Bobbin for fibrous wound material and method for producing the same

ABSTRACT

In order to produce as easily and as economically as possible a bobbin (1) for fibrous wound materials it is suggested that at least one bobbin flange (3) is a flat, annular disk and a frictional welding connection (5) is provided at at least one tube end face (7, 17) of the core tube (2) in the corner region (10) between the core tube (2) and the bobbin flange (3). The parts of the multiple-part bobbin (1) made of light metal are either turned parts or integral forge or extrusion parts (20) composed of a bobbin flange (3) and the core tube (2) which may be, if necessary, cut to the appropriate length so that no costly tool changes are required to produce special bobbin types or to modify the bobbin.

This is a continuation of commonly-owned, U.S. patent application No.07/965,245, filed Jan. 19, 1993, now abandoned.

The invention relates to a bobbin for fibrous wound material, saidbobbin having two flanges that are connected to one another by a coretube, and to a method for producing such a bobbin.

DE 39 08 223 C2 discloses a bobbin for fibrous wound material having thetwo symmetrically divided bobbin halves made of a light metal alloybeing fixedly connected to each other by a frictional welding seam attheir central core tube end faces bluntly abutted upon each other. Forthis purpose, the bobbin halves are produced by extruding requiring,however, relatively expensive extrusion tools. Furthermore,manufacturing the extrusion tools needs a relatively long time andcauses high initial costs. In addition, the shape of the bobbin issubject to geometrical limits determined by the extrusion process. Forexample, producing the bobbin flanges above a predetermined diameter,e.g. >100 mm, is problematic since the wall thicknesses of the bobbinflanges are very small, as compared with the relatively large diameter.

Furthermore, storage of the bobbin halves produced as extrusion parts isrelatively expensive since they may be stacked rather badly and need alot of space. Furthermore, even slight changes in the bobbin shape, e.g.a reduced axial length, cause very complex changes at the extrusion toolsuch that in view of the high tool costs this process is economicalessentially only for large numbers. However, for smaller numbers and aflexible production this process is rarely suitable.

The situation is similar for the bobbin of DE-OS 16 02 319 whose bobbinhalves are formed as molded parts subsequently connected to each otherby inert gas welding. Again, relatively high initial costs for the moldsare necessary which prevents an economical production for small batches.

Furthermore, FR-A-11 30 583 discloses a bobbin made of light metalhaving a core tube completely inserted in two bobbin flanges followed bysoldering along the exterior periphery. However, a homogenous connectioncannot be achieved such that the connection seam tends to break in thecorner region in view of the high axial loading of the bobbin flangesduring winding-up. Furthermore, the interior diameters of the bobbinflanges and the exterior diameter of the core tube in the engagingregion must be manufactured very exactly; otherwise, the result would bea weakening of the connection seam.

Furthermore, GB-A-825 540 discloses a three-part bobbin formed of metalsheet pressing parts subsequently welded together at the exteriorperiphery of the core tube. In this connection, it is rarely possible toachieve a uniform welding-through such that the strength is low.

Accordingly, it is the object of the invention to provide a bobbin forfibrous wound material which may be produced simply and cost-effectivelyeven in small numbers and has a particularly high strength. There shallbe provided a corresponding manufacturing method therefor.

This object is solved by the bobbin and method of manufacturing same, ofthe present invention.

In view of the design of the bobbin made of several parts the individualparts, in particular the flat annular bobbin flanges, may be relativelyeasily produced with any desired diameter, in particular by latheprocessing. In the simplest case the bobbin comprises a core tube andtwo bobbin flanges which are produced on the lathe from correspondingraw parts, i.e. tubes, by cutting-off or separating. Therefore, changesin the geometry of the bobbin, for example a longer core tube, may bemade by simply setting the lathe. Therefore, changes of tools or moldsare no more necessary.

Furthermore, storing is decisively reduced since neither tools norvarious starting materials need to be stored. In contrast, a pluralityof differently dimensioned bobbins may be produced by means of a verysmall number of raw parts, e.g. extruded tubes each for the core tubeand the bobbin flanges. Consequently, the initial costs are drasticallyreduced, as well as the delivery time for special types of bobbins.

It is of particular importance to arrange the frictional welding seam inthe corner or transition region between the core tube end face and theinner side of the bobbin flange facing the core tube since by thismeasure a reliable welding-through of the connecting seam is achievedjust in the highly loaded corner region. Furthermore, during frictionalwelding, the heated material is pressed and condensed thereby whichresults in an essentially homogenous texture, similarly as by forging orextruding, decisively increasing the strength of the bobbin.

Of particular advantage is the embodiment having a rim provided at thebobbin flanges toward the core tube end face, since in this connectionthe frictional zone is limited during frictional welding with the rimbeing then pressed and being replaced by the frictional welding seam. Inthis connection, only relatively low heat dissipates through the bobbinflanges such that there is a minimized loss of heat at the location ofwelding. On the other hand, this results in the provision of the outerfrictional welding bead in the corner region between the core tube andthe inner side of the bobbin flange such that there is a concentrationof material which may be used for rounding during the subsequentfinishing. This definitely prevents the forming of gaps in thetransition region between the core tube and the bobbin flanges wherewound material may be clamped.

With the manufacturing procedure of the present invention it is ofparticular advantage that in simplest manner specific types of bobbinsmay be produced having almost any desired dimensions, in particular inthe case when the forged or extruded part comprising the one bobbinflange and the core tube is cut in length to the desired end length(axial length) prior to the frictional welding to the second disk-typebobbin flange.

Further advantageous modifications are subject of the subclaims.

Hereinafter, the invention is described and explained on the basis ofseveral embodiments illustrated in the drawing. There is shown in:

FIG. 1 an elevational view of the bobbin, partially in section;

FIGS. 2A and 2B, and 3A and 3B an enlarged illustration each of thecorner region of the bobbin in positions joint and welded together;

FIGS. 4 to 6 an enlarged illustration each of modifications of thecorner region; and

FIG. 7 a schematic view of the texture or structure of a bobbin half insection.

FIG. 1 illustrates a bobbin 1 essentially comprising a core tube 2 andtwo end bobbin flanges 3 formed with rotational symmetry about the axis4 of the bobbin 1. The two bobbin flanges 3 are formed as flat, annulardisks having bearing seats 6 in their centers for being fixed to thewinding machine or textile machine. The bobbin flanges 3 are attached tothe two core tube end faces 7 by means of a frictional welding seam 5each. During frictional welding the core tube 2 and the bobbin flange 3are turned against each other, as illustrated by the two opposite arrowsin the left half, and are pressed against each other. In the right halfthe bobbin 1 is illustrated in partial section with the bobbin flange 3being shown in a position as it is positioned immediately before thefrictional welding, followed by the forming of the annular frictionalwelding seam 5 shown in dash-dot lines. The corner or transition regionfrom the core tube 2 to the bobbin flange 3 is illustrated in thesubsequent Figures in enlarged scales. However, the frictional weldingconnection 5 may be accomplished as well in the manner illustrated inFIG. 1 by frictionally welding the core tube end 7 and the inner side 11of the bobbin flange 3 in a blunt-joint manner.

FIG. 2A illustrates the corner region 10 with enlarged scale. The bobbinflange 3 has a projecting rim 8 approximately corresponding to the wallthickness of the core tube 2 and having an axial length x which againcorresponds to the wall thickness of the core tube 2. Since, in general,the wall thickness of the core tube 2 is only several millimeters, therim 8 projects beyond the inner side 11 of the bobbin flange 3 only byseveral millimeters. Therefore, the axial length of the rim 8 is usually2 to 5 mm. In contrast to the flush-type embodiment in FIG. 1 this rim 8serves essentially for omitting introducing heat into the bobbin flange3 during the frictional welding step, such that the loss of heat at thewelding location is minimized. In addition, by this limited heatdissipation in view of the rim 8 lower pressing forces are requiredduring frictional welding. Furthermore, the rim 8 having only a fewmillimeters in height results in an exact position of the frictionalwelding seam 5, in particular the outer formed frictional welding bead9, in the corner region 10 between the core tube 2 and the bobbin flange3 a material concentration being formed there in view of thehot-pressing of the material.

This shape after the frictional welding is illustrated in FIG. 2B. Asmay be seen, the corner region 10 may be rounded when turning(machining) the frictional welding seam 5.

It should be noted that with bobbin flanges 3 being thicker dimensionedin the direction of axis 4, the frictional welding connection 5 may beslightly sunk within the bobbin flange 3, as illustrated in FIGS. 3A and3B. Then, the core tube end, here designated with 17, is circularlytapered, whilst the bobbin flange 3 is provided with a correspondinglyformed conical recess 18 having the same tapering. As may be gatheredfrom FIG. 3B, during frictional welding the tapered core tube end 17 andthe recess 18 engage each other and form the frictional welding seam 5in the corner region 10.

FIGS. 4 to 6 illustrate modified embodiments of the corner region 10,with the core tube end face 7 perpendicularly being aligned to thebobbin axis 4, as in FIGS. 1 and 2. In FIG. 4 the core tube end 7engages a step-type recess 12 in the bobbin flange 3. During frictionalwelding the core tube end 7 is then hot-pressed and, therefore, forms anintimate highly stable connecting seam in the region of the step 12.Similarly, with the embodiment according to FIG. 5, the core tube end 7engages a groove 14 recessed at the inner side 11 and being weldedthereto over the whole surface, since the hot-pressed material of thecore tube corner completely fills the groove 14 and, in addition, formsa highly stable connection with the adjacent material of the bobbinflange 3 with the texture being aligned in the corner region 10. This istrue for the embodiment of FIG. 6 as well, where an annular groove 16 isformed into the inner side 11 having a slightly larger diameter than thecore tube 2. Material hot-pressed during frictional welding penetratesinto this annular groove 16, as indicated by reference numeral 9, andfills the latter and connects to the material of the bobbin flange 3 byforming the outer frictional welding bead 9 simultaneously improving thetexture. The annular groove 16 limits the heat dissipation into thebobbin flange 3 during frictional welding.

For manufacturing the bobbin explained above of light metal, first thetwo bobbin flanges 3 and the core tube 2 are produced preferably fromtube material by means of a lathe processing, in particular by cuttingand, if required, forming of the rim 8. Then, these elements arefrictionally welded, with a preferred procedure the two bobbin flanges 3being simultaneously fricitonally welded in one operational step. Forexample, for this purpose the core tube 2 may be driven and the twobobbin flanges 3 are pressed onto the rotating core tube 2 in a simplestoperation. However, the bobbin flanges 3 may be rotatably driven aswell, whilst the core tube 2 is in rest or rotates in opposition,respectively After the frictional welding, in general it is onlynecessary to remove the frictional welding bead 9 with minimum removalquantities, in particular in the corner region. The inner frictionalwelding bead in the region of the bearing seats 6 may be removedsimultaneously with the bearing treatment, with the further advantagethat the inner frictional welding bead is better accessible and may becontrolled more exactly, as compared with the central embodimentaccording to DE 39 08 225 C2. This enables an improved checking of thewelding seam and, therefore, a better quality control. The frictionallywelded bobbin 1 is preferably hardened prior to the finishing up to ahigher strength. As a material, in particular AlMn-alloys are adapted.

FIG. 7 illustrates a particularly advantageous embodiment of thebobbin 1. Here, the left bobbin flange 3 is formed together with thewhole core tube 2 as an integral forge or extruded element 20 whose coretube end 7 is then only frictionally welded, as explained in connectionwith FIG. 1, to the right bobbin flange 3. As shown, the weld bead isremoved such that the weld smoothly merges with the bobin surfaces.Here, in the half-section in the lower portion of the Figure, thetexture of the light metal is schematically illustrated, with thepredominantly axially directed texture of the sunk, extruded, or forgedindividual parts being condensed in the corner region 10 by thehot-pressing of the core tube end 7 and being deflected into the radialdirection enforcing this transitional region suspicious of breaking.Accordingly, the frictionally welded corner region 10 has a similarlyhigh strength as the opposite transitional region at the left bobbinflange which is manufactured by forging or extrusion with anon-interrupted and, therefore, highly stable texture.

Furthermore, it is of importance that the forged or extruded element 20may be adapted to the desired length of the bobbin by correspondinglycutting it off, for example, by turning-off, sawing-off, etc., asindicated by several separating lines 21. Therefore, only a few forgingor extruding molds are required for manufacturing a plurality ofdifferent bobbin lengths. The subsequent suggested frictional weldingwith the disk-type bobbin 3 results in a simple and fast manufacture ofa highly stable bobbin 1.

We claim:
 1. A method for producing a bobbin assembly to be used forwinding fibrous material thereon, comprising the steps of:providing acylindrical core tube and first disk-type bobbin flange at a one end ofthe core tube as an integral forge or extrusion part, said core tubehaving a free end opposite the one end; frictional welding a seconddisk-type bobbin flange to the free end of said core tube to form abobbin assembly, in a manner that a resulting frictional welding bead isdisposed exactly in a corner formed between a face of the second flangeand the free end of the core tube, thereby causing a smooth transitionof metallurgical grain line orientation between the second flange andthe core tube.
 2. A method, according to claim 1, wherein the core tubehas a wall thickness, and further comprising:prior to frictional weldingthe second flange to the core tube, providing the second flange with arim projecting from the face thereof, said rim having a thickness andhaving a height, each of which are approximately equal to the wallthickness of the core tube.
 3. A method, according to claim 2, furthercomprising:ensuring, during frictional welding, that the projecting rimis converted in the frictional welding step to become part of thefrictional welding bead.
 4. A method, according to claim 1, wherein:saidcore tube and first flange exhibit a first rigidity; and afterfrictional welding said core tube and second flange, the welded secondflange and core tube exhibit a second rigidity approximately equal tosaid first rigidity.
 5. A method, according to claim 1, furthercomprising:after frictional welding, lathe processing said bobbinassembly to at least partially remove said frictional welding bead insaid corner.
 6. A method, according to claim 1, further comprising:afterfrictional welding, lathe processing said bobbin assembly to completelyremove said frictional welding bead in said corner such that the weldsmoothly merges with the bobin surfaces.
 7. A method, according to claim1, further comprising:after frictional welding, heat-hardening saidbobbin assembly.
 8. A method, according to claim 1, furthercomprising:after frictional welding, heat-hardening said bobbinassembly; and after heat-hardening said bobbin assembly, latheprocessing said bobbin assembly to at least partially remove saidfrictional welding bead in said corner.
 9. A method, according to claim1, further comprising:after frictional welding, heat-hardening saidbobbin assembly; and after heat-hardening said bobbin assembly, latheprocessing said bobbin assembly to completely remove said frictionalwelding bead in said corner such that the weld smoothly merges with thebobin surfaces.
 10. A method, according to claim 1, furthercomprising:prior to frictional welding, cutting off the free end of thecore tube to predetermine a final length for said completed bobbinassembly, taking into account any conversion of material resulting fromfrictionally welding the free end of the core tube to the second flange.11. Bobbin assembly kit, comprising:a cylindrical core tube made oflight metal, having a one end and an other end opposite the one end, thecore tube having a wall with a thickness; and two bobbin flanges, eachformed as a flat annular disk having a rim projecting from a mainsurface thereof, said main surface being oriented, in use, towards arespective end of the core tube, said rim having a radial thicknesssubstantially equal to the thickness of said core tube wall, said rimhaving a projecting height substantially equal to the thickness of saidcore tube wall, said rim being converted, when said flange is frictionalwelded to said core tube, to a frictional welding beam disposed exactlyin a corner formed between the flange and the respective end of the coretube.
 12. Bobbin assembly kit, according to claim 11, wherein:theprojecting height of the rim, prior to frictional welding, is about 2 to5 mm.